Phosphorescent emitting compositions

Abstract

A light emitting composition comprising a central platinum group transition metal and a bidentate ligand comprised of at least one pyridyl group with an electron donating substituent in the 4 position forming a six membered ring complex. The electron donating substituent is represented by an alkyl, aryl or amine group. The platinum group transition metal may be selected from the group consisting of platinum, palladium, iridium, rhodium, ruthenium, and osmium. Additionally, OLED devices are provided, each of the OLED devices comprising a light emitting layer that includes one of the light emitting compositions.

I claim: 
     
       1. A light emitting composition comprised of a central platinum group transition metal (M) selected from platinum, palladium, iridium, rhodium, ruthenium, and osmium and a bidentate ligand comprised of at least one pyridyl group including an electron donating substituent in the 4 position and forming a six membered ring complex, wherein the composition has the structure: 
       
         
           
           
               
               
           
         
       
       and
 wherein R is independently selected from an alkyl group and an aryl group, and 
 n=1, 2, or 3. 
 
     
     
       2. The composition of  claim 1 , wherein the platinum group transition metal is platinum. 
     
     
       3. The composition of  claim 2 , wherein the composition has the structure: 
       
         
           
           
               
               
           
         
       
     
     
       4. The composition of  claim 2 , wherein the composition has the structure: 
       
         
           
           
               
               
           
         
       
     
     
       5. An OLED device comprising a light emitting layer including a light emitting composition comprised of a central platinum group transition metal (M) selected from platinum, palladium, iridium, rhodium, ruthenium, and osmium and a bidentate ligand comprised of at least one pyridyl group including an electron donating substituent in the 4 position and forming a six membered ring complex wherein the composition has the structure: 
       
         
           
           
               
               
           
         
       
       and
 wherein R is independently selected from an alkyl group and an aryl group, and 
 n=1, 2, or 3. 
 
     
     
       6. The OLED device of  claim 5 , wherein the platinum group transition metal is platinum. 
     
     
       7. The OLED device of  claim 6 , wherein the composition has the structure: 
       
         
           
           
               
               
           
         
       
     
     
       8. The OLED device of  claim 6 , wherein the composition has the structure: 
       
         
           
           
               
               
           
         
       
     
     
       9. A light emitting composition comprised of a central platinum group transition metal and a bidentate ligand comprised of at least one pyridyl group including an electron donating substituent in the 4 position and forming a six membered ring complex, wherein the composition has the following structure: 
       
         
           
           
               
               
           
         
       
     
     
       10. An OLED device comprising a light emitting layer including a light emitting composition comprised of a central platinum group transition metal and a bidentate ligand comprised of at least one pyridyl group including an electron donating substituent in the 4 position and forming a six membered ring complex wherein the composition has the structure: